How do I install 70mm brake blocks without them rubbing the tyre?

If you have ever spent a Saturday afternoon trying to fix a “rubbing” sound on your bike, you know how infuriating it can be. You tighten the bolt, spin the wheel, and scuff—the brake pad is touching the tyre. You move it down, and suddenly half the pad is hanging off the rim, doing absolutely nothing to stop you. 

Installing 70mm brake blocks is a common task for UK commuters and mountain bikers, but getting that perfect alignment is where most people struggle. If the pad touches the rubber of the tyre, it will cause a blowout in a matter of miles. If it sits too low, you lose stopping power and ruin your rims. In this guide, we will walk through the “toe-in” technique and the exact steps to get your brakes silent, sharp, and safe. 

The Problem: Why “Close Enough” Isn’t Good Enough 

Most V-brakes use a 70mm long pad because the larger surface area provides better stopping power, especially in the wet and dreary British weather. However, because they are so long, even a tiny angle error at the mounting bolt is magnified at the ends of the pad. 

The two biggest issues riders face are: 

1. Tyre Rub:The pad sits too high, friction heats up the tyre sidewall, and the tube eventually pops.
2. Brake Squeal:The pad hits the rim perfectly flat, causing it to vibrate at a high frequency. This creates a deafening screech that can be heard three streets away.

The Solution: The Step-by-Step Alignment Guide 

To fix this, you need a 5mm Allen key and about ten minutes of patience. Follow these steps to get a professional finish. 

1. Loosen and Reset

Start by loosening the nut holding the brake block. You don’t need to take it off; just make it loose enough that the pad can wiggle freely. Check your “washers” (the little concave spacers). These allow the pad to tilt at different angles. Make sure they are clean and not seized up with road grit. 

2. The Height Check

Pull the brake lever so the pad touches the rim. The goal is to have the pad sitting exactly in the middle of the metal braking surface. Ensure there is a clear 1mm to 2mm gap between the top of the brake block and the start of the tyre rubber. 

3. Mastering the “Toe-In”

This is the secret to silent brakes. Instead of the pad hitting the rim flat, you want the front of the pad (the bit facing the front of the bike) to touch the rim slightly before the back. 

• The 10p Trick: Slide a 10p coin (or a folded piece of thin cardboard) under the rear end of the brake block before you tighten it.
• The Squeeze: Squeeze the brake lever hard. This holds the pad in place against the rim and the coin.

4. Tighten and Test

While holding the lever squeezed tight, tighten the 5mm bolt. When you release the lever and remove the coin, the front of the pad should be slightly closer to the rim than the back. This “toe-in” prevents vibration and ensures a smooth, quiet stop. 

Reliability in the Rain 

In the UK, we don’t just ride in the sun. We ride through puddles, mud, and road salt. Standard, cheap rubber pads often turn into a “grinding paste” that eats your rims when they get wet. To avoid this, you need a compound specifically designed for the climate. 

The Laxzo 70mm All-Weather V-Brake Pads are engineered with deep grooves to channel water and grit away from the braking surface. This means that once you have gone through the effort of aligning them perfectly, they won’t just slide across a wet rim, they will actually bite.  

The 70mm length provides that crucial surface area needed for heavy hybrids or mountain bikes, making them a reliable choice for the daily school run or the muddy weekend trail. 

FAQs

1.Why does my brake pad feel “sticky” and won’t pull back from the rim? 

This is usually caused by the tension springs on the brake arms. Check the small “limit screws” on the side of the V-brake arm. Tightening the screw increases the spring tension, pulling the pad further away from the wheel. 

2.How do I know when to replace my 70mm blocks? 

Most pads have “wear indicator” lines or grooves. When the rubber has worn down so much that the grooves have disappeared, it is time for a new set. Never let them wear down to the metal holder, as this will destroy your wheel. 

3.Does it matter which way the pads point? 

Yes. Most 70mm pads are directional. Look for a small arrow on the rubber that says “Front” or “Direction.” Installing them backwards can lead to the pads being pulled out of their holders under heavy braking. 

4.My brakes are still squeaking after I aligned them. What now? 

Give your rims a good scrub. Use a clean rag with a bit of isopropyl alcohol (or even just soapy water) to remove the layer of black grime and oil. A clean rim is a quiet rim. 

5.Can I use these 70mm pads on a road bike? 

Usually, no. Road bikes with “calliper” brakes typically use much smaller 50mm or 55mm pads. These 70mm blocks are specifically designed for V-brakes and cantilever systems found on mountain bikes, hybrids, and trekking bikes.